Salt-coated Mg granules are prepared in various ways, such as disclosed, e.g., in U.S. Pat. Nos. 3,881,913; 4,186,000; and 4,182,498.
U.S. Pat. No. 3,881,913 discloses a hydrochemical treatment of salt-coated Mg granules using a 1-10% solution of alkali metal bichromate (viz. potassium bichromate) at 10.degree.-35.degree. C. with the weight ratio of granules to solution being from 1:2 to 1:20. The hydrochemical treatment removes a substantial amount of the salt from the Mg.
U.S. Pat. Nos. 4,186,000 and 4,182,498 disclose the preparation of Mg granules which each have a thin protective salt coating. The salt coating helps protect the Mg metal from hydrolysis or oxidation by air, especially wet air.
It is desired to produce substantially salt-free Mg particles, for applications where salt is desirably absent, by removing salt from salt-coated Mg particles.
It is an object of the present invention to substantially remove salt from salt-coated Mg particles, regardless of their size and shape, in a manner which substantially avoids hydrolysis of the Mg particles, or of leaching away or reacting away a significant amount of the Mg metal.
A further object is to substantially remove the salt from salt-coated Mg particles by means which leave the Mg particles with a thin protective passivated surface.